Room Night Light Exposure May Affect Sleep Quality, Blood Pressure

A recent study indicates that having a night light on when sleeping may affect a person’s sleeping quality as well as blood pressure and diabetes risk. The said study, conducted by researchers from Brigham and Women’s Hospital and Harvard Medical School in Boston, Mass., indicated that exposure to electrical light in between dusk and bedtime may affect the level of melatonin in the body. The study was accepted for publication at the Journal of Clinical Endocrinology & Metabolism (JCEM), the journal; of The Endocrine Society.

Melatonin levels can affect certain body processes that is regulated by melatonin signaling such as sleep, body temperature regulation, blood pressure as well as glucose conversion. Melatonin is a natural body hormone usually produced the pineal gland in the brain at night. The study conducted aim to understand whether light exposure at night may have an effect on the body’s melatonin production.

The study involved 116 participants aged between 18 to 30 years old who were exposed to either room light or dim light 8 hours before bedtime for five consecutive days. An intravenous catheter was also inserted in the arms of the participants to enable continuous collection of blood plasma every 30- 60 minute for measurement of melatonin.

The results showed that exposure to room light by about 90 minutes before bedtime can shorten melatonin production compared to being exposed to dim light. Light exposure during the usual sleeping hours suppressed melatonin by as much as 50 percent.

According to Joshua Gooley, PhD, of Brigham and Women’s Hospital and Harvard Medical School in Boston, Mass. and lead author of the study, “Our study shows that this exposure to indoor light has a strong suppressive effect on the hormone melatonin. This could, in turn, have effects on sleep quality and the body’s ability to regulate body temperature, blood pressure and glucose levels.”

“Given that chronic light suppression of melatonin has been hypothesized to increase relative risk for some types of cancer and that melatonin receptor genes have been linked to type 2 diabetes, our findings could have important health implications for shift workers who are exposed to indoor light at night over the course of many years,” he further added.

Source: The Endocrine Society. “Room light before bedtime may impact sleep quality, blood pressure and diabetes risk.” ScienceDaily 13 January 2011. 14 January 2011 <http://www.sciencedaily.comĀ­ /releases/2011/01/110113082716.htm>


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